JP2003170625A - Method for driving optical write head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly precisely correct a deviation in a vertical scanning direction of a light point array on an optical drum in an optical write head having light- emitting element array chips mounted in a linear arrangement. <P>SOLUTION: Image data corresponding to the self-scanning light-emitting element array chips is arranged together with a shift into a memory prepared for image data in accordance with a distance between array chips. Image data is read out sequentially from the memory in a physical arrangement order of the memory, thereby driving each array chip. A generation timing of a start pulse to be supplied to a start pulse line of the self-scanning light-emitting element array chip is adjusted in accordance with a mounting position deviation amount for each array chip. The process of arranging the image data with the shift into the memory is carried out by a software when the image data is developed to the memory. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving an optical writing head used in an optical printer, and more particularly to a method for correcting light emitting point array position deviation in the sub-scanning direction.

[0002]

2. Description of the Related Art A writing head of an optical printer (hereinafter referred to as an optical writing head) is a light source for exposing a photosensitive drum to light and has a light emitting point array composed of a light emitting element array. A principle diagram of an optical printer having an optical writing head is shown in FIG. On the surface of the cylindrical photosensitive drum 2,
A material (photoreceptor) having photoconductivity such as amorphous Si has been made. This drum is rotating at print speed. The photoconductor surface of the rotating drum is uniformly charged by the charger 4. Then, the optical writing head 6 irradiates the photosensitive member with the light of the dot image to be printed, and neutralizes the charging where the light hits. Subsequently, the developing device 8 applies toner onto the photoconductor according to the charged state of the photoconductor. Then, the transfer device 10 transfers the toner onto the sheet 14 sent from the cassette 12. The sheet of paper is heated and fixed by the fixing device 16 and is fixed to the stacker 18. On the other hand, the erased lamp 2
At 0, the charge is neutralized over the entire surface, and the cleaning device 22 removes the remaining toner.

The structure of the optical writing head 6 is shown in FIG.
The optical writing head 6 is composed of a light emitting element array 24 and a rod lens array 26, and the focal point of the lens is located on the photosensitive drum 2. The rod lens array is
For example, it is configured by stacking rod lenses in a bag.

On the other hand, the present inventors have paid attention to a three-terminal light emitting thyristor having a pnpn structure as a constituent element of a light emitting element array, and have already filed a patent application (Japanese Patent Laid-Open No. 1-238962) that self-scanning of a light emitting point can be realized. Japanese Patent Laid-Open No. 2-1
No. 4584, Japanese Unexamined Patent Publication No. 2-92650, Japanese Unexamined Patent Publication No. 2-92651), it is easy to mount as a light source for an optical writing head, the light emitting element pitch can be made fine, and a compact light emitting element array can be manufactured. Etc.

Furthermore, the present inventors have proposed a self-scanning light-emitting element array having a structure in which a transfer element array composed of a light-emitting thyristor having a pnpn structure is used as a shift register and is separated from the light-emitting element array (Japanese Patent Laid-Open Publication No. HEI 2). -2636
No. 68).

FIG. 3 shows the self-scanning light emitting element array.
Equivalent circuit diagram of (2-phase drive 1 point lighting common cathode type)
Show. This light emitting element array includes switch elements T (1) to
From T (4), the writing light emitting elements L (1) to L (4)
Become. Use a diode connection for the switch element configuration.
I am V_GKIs a power supply (usually 5V) and a load resistance R
_L Through the gate electrode G of each switch element₁ ~ G₃ Connected to
Has been done. Also, the gate electrode G of the switch element₁ ~ G
₃ Is also connected to the gate electrode of the writing light-emitting element.
It The gate electrode of the switch element T (1) has a start pattern.
Ruth φ_S Is added to the anode electrode of the switch element.
Of the transfer clock pulses φ1 and φ2 are alternately applied.
Write on the anode electrode of the light emitting element for writing.
Signal φ_I Has been added.

The operation will be briefly described. First, the transfer clock
When the voltage of pulse pulse φ1 is high level, the switching element T
It is assumed that (2) is on. At this time, the gate electrode
G₂ Potential is V_GKFrom 5 V to almost zero V.
The effect of this potential drop is diode D₂ By gated
Pole G₃ To about 1 V (diode D
₂ Forward voltage (equal to the diffusion potential) of
It However, the diode D₁ Is in reverse bias
Gate electrode G₁ No potential is connected to the gate
Pole G₁ The potential remains at 5V. Light-emitting thyristor
The gate potential is the gate electrode potential + the diffusion potential of the pn junction (about 1
V), the next transfer clock pulse φ2
H level voltage is about 2V (switch element T (3) is turned on
Is higher than the required voltage) and about 4V (switch
Switch element T (5) to turn on)
If set to, only the switch element T (3) is turned on,
Other switch elements can be left off
It Therefore, the on state changes with two transfer clock pulses.
Will be sent.

The start pulse φ _S is a pulse for starting such a transfer operation, and the start pulse φ S
At the same time when _{S is set} to the L level (about 0 V), the transfer clock pulse φ2 is set to the H level (about 2 to about 4 V), and the switch element T (1) is turned on. Immediately after that, the start pulse φ _S is returned to the H level.

Now, assuming that the switch element T (2) is in the ON state, the potential of the gate electrode G ₂ becomes lower than V _GK and becomes almost 0V. Therefore, if the voltage of the write signal φ _I is the diffusion potential of the pn junction (about 1 V) or more,
The light emitting element L (2) can be in a light emitting state.

On the other hand, the gate electrode G ₁ is about 5V and the gate electrode G ₃ is about 1V. Therefore, the writing voltage of the light emitting element L (1) is about 6 V,
The write voltage of (3) is about 2V. From this, the voltage of the write signal φ _I which can be written only to the light emitting element L (2) is in the range of 1 to 2V. Light-emitting element L (2) is on,
That is, when entering the light emitting state, the light emission intensity is the write signal φ.
It is determined by the amount of current flowing through _I , and it is possible to write images at any intensity. In order to transfer the light emitting state to the next light emitting element, the voltage of the write signal φ _I line is once set to 0.
It is necessary to turn off the light emitting element which is emitting light to V.

Such a self-scanning light emitting device array is
It has a feature that the number of bonding pads may be smaller than that of a normal light emitting element array. This feature has the advantage that the chip area can be reduced.

When the self-scanning light emitting element array is applied to an optical writing head or the like, when a plurality of light emitting element array chips are arranged in one direction and an image is output, the image data in the memory is synchronized with a desired timing. Then, the light emitting elements are transferred to the corresponding light emitting elements on the light emitting element array chip to cause the light emitting elements to emit light.

[0013]

However, in the conventional optical writing head, when arranging a plurality of light emitting element array chips in one direction, distortion of the head itself, mounting accuracy when mounting the array chips, and Due to fluctuations in the lens array arrangement or the like, the arrangement of the chips deviates in a direction (hereinafter referred to as the sub-scanning direction) orthogonal to the chip arrangement direction (hereinafter referred to as the main scanning direction). When a light spot array is projected onto the photosensitive drum by using such an optical writing head, the array chips are arranged with a shift in the sub-scanning direction, so that the light spot array on the photosensitive drum is displaced in the sub-scanning direction. As a result, the output image also has a shift corresponding to the shift width of the array chip.

In the conventional optical writing head, in order to correct the deviation in the sub-scanning direction, image data is called from the image memory for each array chip, and a delay circuit for time adjustment is used to make the corresponding light emitting element on the array chip. This is done by adjusting the timing of transferring image data.

Therefore, it is necessary to incorporate a circuit for adjusting the timing for each array chip, and since the timing is adjusted for each array chip, the set value of the timing is stored for each array chip. In addition, it is necessary to synchronize the generation timing of the start pulse supplied to the start pulse line with this set value, which causes a problem that the circuit configuration becomes complicated.

An object of the present invention requires a circuit for calling image data from the image memory for each light emitting element array chip and adjusting the timing of transferring the image data to the corresponding light emitting element on the light emitting element array chip. It is an object of the present invention to provide a method of driving an optical writing head, which can correct the deviation of the light spot array on the photosensitive drum in the sub-scanning direction.

Another object of the present invention is to provide a high-definition deviation in the sub-scanning direction of the light spot array on the optical drum during image output, even if the mounting accuracy of the light-emitting element array chip in the sub-scanning direction is relaxed. An object of the present invention is to provide a method of driving an optical writing head that can be corrected.

[0018]

The present invention provides a method of driving an optical writing head in which a plurality of time-division driven light emitting element array chips in which a plurality of light emitting elements are arranged in rows are arranged. It is characterized in that the timing of turning on the first light emitting point of the array is adjusted by the amount of positional deviation of each light emitting point projected on the photosensitive drum in the sub-scanning direction.

The light emitting element array chips are arranged and mounted along one or two rows of substantially straight lines, and image data for driving each light emitting element array chip in accordance with the timing of lighting the first light emitting point. It is desirable to shift the timing of.

Further, according to the present invention, a plurality of time-divisionally driven light emitting element array chips in which a plurality of light emitting elements are arranged in a row are arranged in a staggered pattern, and are orthogonal to the arrangement direction of the light emitting element array chips. In a method of driving an optical writing head, in which each light emitting element array chip is mounted in the same direction by making the interval between the light emitting element arrays of the light emitting element array chips an integral multiple of the distance on the photosensitive drum that moves in one line time, The timing of lighting the first light emitting point of the array is adjusted by the amount of positional deviation of each light emitting point projected on the photosensitive drum in the sub-scanning direction, and each light emitting element is adjusted in accordance with the timing of lighting the first light emitting point. It is characterized in that the timing of image data for driving the array chip is shifted.

In order to shift the timing of the image data, it is desirable to collectively shift and arrange the images in a memory prepared for the image, and sequentially read the image data from the memory in the physical memory arrangement order. When collectively shifting and arranging in the memory prepared on the memory prepared for, it is desirable to write the data indicating no image writing to the address where the image data was not written by the shift.

Further, the amount of positional deviation is stored in the storage means for each chip or for each block in which a plurality of chips are grouped together, and timing is generated using the amount of positional deviation stored in the storage means. It is desirable that the first light emitting point is turned on by using the generated timing.

Further, the timing of turning on the first light emitting point is preferably transferred in synchronization with the image data for each chip or for each block in which a plurality of chips are grouped together, and the image data is shifted. The process of arranging in the memory is preferably performed by software when the image data is expanded in the memory.

Further, it is preferable that the light emitting element array chip is a self-scanning type light emitting element array chip.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 4 is a view showing a state in which the self-scanning light emitting element array chips according to the present invention are arranged on the head in a substantially linear manner. In FIG. 4, the x direction is the main scanning direction of the chip, and the light emitting point on each self-scanning light emitting element array chip is sequentially shifted in the x direction from the leftmost light emitting point. An image is written depending on whether or not each light emitting point is turned on at this shifted timing. On the other hand, the y direction is the sub-scanning direction, which is the same as the paper feeding direction.

Self-scanning light emitting element array chip (C₀，
C_l, C₂, C₃) 29 has 256 light emitting elements 33
It is provided in a straight line at regular intervals, and is provided in a straight line.
The bonding pad 31 is provided along the light emitting element 33.
Has been. Each self-scanning light emitting element array chip
(C₀, C_l, C₂, C₃) 29 should be arranged in a straight line
However, due to mechanical accuracy, there is a deviation in the y direction.
It Here, based on the light emitting point center line of the C3 chip,
Displacement L₀, L_l, L₂, L₃Was measured, L
₀= -11 μm, L_l= -15 μm, L₂= -5 μm,
L₃= 0 μm.

Now, the light emitting element array chips C _{0 to} C
_When all ₃ are lit and a straight line is drawn, chip misalignment L ₀ ~
Due to the influence of L ₃ , the straight line is distorted and drawn as shown in FIG. Each band in FIG. 5 is an overlapping drawing of spot light emitted from the light emitting element of each chip. In addition,
The band for each chip is not parallel to the x axis because the paper advances in the y direction while drawing one line. Here, the light emitting point interval is 1200 dpi (1200 light emitting points are aligned per inch. About 21.16 μm
It is considered that the distance traveled by the paper while drawing one line is 21.16 μm.

FIG. 6 shows how the data used to draw FIG. 5 is stored on the memory. This Figure 6
Is read out in the physical memory arrangement order. The array in the vertical column direction is image data corresponding to the light emitting points of each light emitting element array chip, and (WXYZ) is WXYZ.
It represents the value (0 or 1) of the (h) th data ((h) indicates that it is a hexadecimal number. Unless otherwise specified, it is indicated by a decimal number). Note that W (h) is the line number of the image data, and X (h) is the chip number (0, 1, 2,
3) and YZ (h) represent the light emitting point number of each chip. For example, (123E) indicates that it is the image data of the 3E (h) th light emitting point of the second chip on the first line. In FIG. 6, when looking at the data in the horizontal direction, only X is always different, and the same data is lined up for the other W, Y, and Z. That is, the data of the same light emitting point number on the same line are read at the same timing.

Next, in order to correct the shift in the y direction, the data was shifted on the memory. FIG. 7 shows how the data is stored on the memory at this time. As mentioned above, FIG.
Of the chip in the y direction is L ₀ = −11 μm,
L ₁ = -15 μm, L ₂ = -5 μm, and L ₃ = 0 μm. Since the paper is sent in the + y direction, the start of each line drawing is -11 μm, with C ₃ as the reference.
It may be delayed by -15 μm, −5 μm, or 0 μm. On the contrary, when Cl having the smallest amount of delay is considered as a reference, it may be delayed by 4 μm, 0 μm, 10 μm, and 15 μm, respectively. Since the distance sent in the sub-scanning direction is 21.16 μm while 256 light emitting points are sequentially turned on, 4 / 2.16 × 256≈30 (h),
0, 10/2 1.16 x 256 ≈ 79 (h), 15/2
1.16 × 256≈B5 (h). In the case of a two-phase driving self-scanning light emitting element, since the start is started by the product of the start signal and the φ1 clock pulse, it is necessary to select an even number of light emitting point shifts.
(H), 0, 7A (h) and B6 (h) were taken.

FIG. 7 also shows start timing data for each chip. The data in this column is 0 when YZ (h) = 00 (h), and 1 is entered in other cases. The self-scanning light emitting element used here is one in which the first thyristor of the shift section is turned on when the start pulse is 0 and the φ1 clock pulse becomes 0 → 1.

As described above, by arranging the start timing data on the memory and reading them in the physical memory arrangement order, it is possible to synchronize the image data and the start timing without using a special circuit. The result of drawing by sequentially reading the image data of FIG. 7 is shown in FIG.
Shown in.

With this method, fine adjustment is possible with the resolution of the value obtained by dividing the distance of the paper fed during drawing one line by half the number of light emitting points. In this embodiment, 21.16.
Adjustment in μm / 128 = 0.16 μm unit is possible.
It should be noted that 0 (data indicating no image writing) is designated at the image memory address where no data has been written.
Further, the process of shifting the image data and arranging the image data in the memory may be performed by software when the image data is expanded on the memory.

Next, a second embodiment of the present invention will be described.

In the first embodiment, the start timing is expanded on the memory together with the image data and transferred at the same time, so that the deviation in the y direction can be corrected without preparing a special device. However, the memory capacity is doubled, and the line for transmitting data is also doubled. Therefore,
In the second embodiment, a device for generating the start timing is separately prepared. FIG. 9 is a circuit diagram of an apparatus for generating start timing, and FIG. 10 is a timing chart for explaining the operation.

The φ1 clock pulse 61 is input to the CLK terminal of the counter 70, the reset pulse 60 is input to the RST terminal, and the counter 70 rises the φ1 clock pulse 61 after the reset pulse 60 rises. Count the number. On the other hand, the memories 53-0 to 53-
In 3, the start timing set value for each chip is stored.

The comparator 52-0 compares the set value of the memory 53-0 with the count data 80 output from the counter 70. If they match, it is "1", and if they do not match, "0". And outputs the comparator output 54-0. NAND
The gate 51-0 takes the NAND between the comparator output 54-0 and the φ1 clock pulse 61, and outputs the start pulse 5
Outputs 5-0.

Similarly, the comparators 52-1 to 52-3 compare the set values of the memories 53-1 to 53-3 with the count count data 80, and when they match each other, the count value is "1". Comparator outputs 54-1 to 54-3 set to "0" at the time
Are output respectively. Each NAND gate 51-1 to 51
-3 takes a NAND between the comparator outputs 54-1 to 54-3 and the φ1 clock pulse 61, and starts pulse 5
5-1 to 55-3 are output respectively.

FIG. 10 shows a reset pulse 60, a φ1 clock pulse 61, a φ2 clock pulse 62, a comparator output 54-0 to 54-3, and a start pulse 55-0 to 55-.
3 shows the timing of 3.

Next, a third embodiment of the present invention will be described.

In the second embodiment, a counter, a comparator, etc. are required, and the circuit structure is complicated. Therefore,
(Number of light emitting elements included in one self-scanning light emitting element)
An effect similar to that of the second embodiment can be obtained by preparing half the memory of × (the number of chips), storing the start pulses 55-0 to 55-3 in FIG. 10 and sequentially reading the pulses in synchronization with the image data. Was obtained.

Next, a fourth embodiment of the present invention will be described.

In the fourth embodiment, the light emitting element array chips are mounted by arranging them in two rows of straight lines and two rows of substantially straight lines such as a staggered arrangement.

FIG. 11 shows a state in which the self-scanning light emitting element array according to the present invention is arranged in a staggered manner on the head. In FIG. 11, the x-axis direction is the main scanning direction of the chip and the y direction is the sub-scanning direction, which is the same as the paper feeding direction. Self-scanning light emitting element array chip (C ₀ ,
C _l , C ₂ , C ₃ ) 29 is provided with bonding pads 31 at both ends, and 256 light emitting elements 3 are provided between them.
3 are linearly provided at intervals p. In addition, the self-scanning light emitting element array chip 29 is arranged so that the light emitting elements 3 are arranged in the y direction.
The array chips are arranged in a zigzag pattern in a z-direction by shifting a distance corresponding to n times the interval p of 3 (n is an integer), and are fixed on the substrate with an adhesive.

Consider the case where the paper feeding speed advances by p during the time when the self-scanning light emitting element array draws one line. At this time, the distance x ₁ between the light emitting points at both ends in the x direction,
By making all x ₂ and x ₃ equal to p, the interval of the light emitting elements 33 in the x-axis direction is set to a constant value p through all the plurality of self-scanning light emitting element array chips.

The self-scanning light emitting element array chip 2
Since all 9 use the same design,
Number chip C₀, C₂And odd numbered chip C_l, C₃Vs
It is placed facing. Therefore, the transfer direction of the light emitting point is C
₀, C₂Then from left to right, C _l, C₃Then from right to left
Has become.

In an ideal chip placement, x₁= X₂= X
₃= P, d_l= D₃= Np (n is a natural number), d₂= 0
is there. Where d_l, D₂, D₃Is C₀Center of light emitting point
C based on the line_l, C₂, C₃Center line of each chip emission point
Is the distance in the y direction. However, the mechanical
The value deviates from the ideal value due to accuracy. Image data now
An example of drawing a straight line without adjusting the timing of Figure 1
2 shows. If this is left as it is, the level difference is large and the image quality is
Will be Therefore, d_l, D₂, D₃Equivalent to
Therefore, as in the first embodiment, there is a shift in the memory.
You In this case, C ₀On the other hand, the data of the nth chip is
d_n/21.16×256 delay (here
And d_nIs a value expressed in μm. ) Result of actual measurement, d_l
= 48 μm, d₂= 4 μm, d₃= 44 μm.
Therefore, the start timing of each chip is C_lso
48 / 2.16 × 256 = 580 bits, C₂4 /
21.16 × 256 = 48 bits, C₃At 44/21.
16x256 = just shift the data by 532 bits
Yes. In addition, the start pulse timing is
Similar to the embodiment, only when YZ (h) = 00 (h)
Prepare a data string to be "1". As a result of this correction,
I was able to successfully connect straight lines like No. 13.

Here, the start pulse timing is provided in the memory as in the first embodiment, but it may be generated in a separate circuit as in the second and third embodiments. In the case of the second and third embodiments, it is not possible to specify a shift of more than half the number of light emitting points of the self-scanning light emitting element array. For example, when the image data of C _l is shifted by 580 bits, half of 290 is stored in the start timing set value memory in the second embodiment, but a value of 128 or more is not stored. Therefore, it suffices to insert the remainder system 34 (290-128-128 = 34) in 128 of 290. In this case, C _l starts with a delay of 68 bits, but the image data is 0 (data indicating no image writing).
So there is no problem.

In the above embodiments, the case where one chip includes one self-scanning light emitting element having 256 light emitting points has been described, but the present invention is not limited to this configuration, and the number of light emitting points is Any number of self-scanning light emitting elements included in one chip may be selected.

In addition to the self-scanning light emitting element, in the case of a light emitting element which drives a light emitting point in a time division manner, by adjusting the image data and the start timing according to the present invention,
It is possible to adjust the deviation in the y direction.

Further, in the above-mentioned embodiments, the case where the light emitting element array chips are arranged in one row and approximately two rows has been described, but it can also be used in the case where they are arranged in three rows or more. It can also be used when chips are randomly arranged in the sub-scanning direction.

Further, in the above-described embodiments, the adjustment is performed for each light emitting element array chip, but a plurality of chips may be integrated into one block and the same correction may be performed in the same block. Good. As a result, the hardware required for correction and the cost for collecting data can be reduced.

[0053]

As described above, according to the present invention, the image data is called from the image memory for each array chip by simply shifting the image data on the memory based on the mounting state of the light emitting element array chip. Correcting a shift in the y (sub scanning direction) direction of the light spots on the optical drum without adding a special circuit for adjusting the timing of transferring image data to the corresponding light emitting element on the array chip. You can

Further, according to the present invention, since the generation timing of the start pulse supplied to the start pulse line for each array chip is adjusted according to the mounting position deviation amount for each array chip, the y direction of the light emitting element array chip is adjusted. Even if the mounting accuracy of is reduced, y of the light spot array on the optical drum is output during image output.
The deviation in direction can be corrected with high precision.

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of an optical printer including an optical writing head.

FIG. 2 is a diagram showing a structure of an optical writing head.

FIG. 3 is a self-scanning light-emitting element array chip (2-phase drive 1
It is an equivalent circuit diagram of a basic structure of a point lighting type cathode common type).

FIG. 4 is a diagram showing a state in which self-scanning light emitting element array chips according to the present invention are arranged in a substantially straight line on a head.

FIG. 5 is a diagram showing an example of an image when a straight line is drawn without shifting the image data on the memory.

FIG. 6 is an image diagram of a memory when the image data is arranged in the memory without being shifted.

FIG. 7 is an image diagram of a memory when the image data is arranged in the memory in a shifted state.

FIG. 8 is a diagram showing an example of an image when a straight line is drawn by shifting image data on a memory.

FIG. 9 is a circuit configuration diagram of a device that generates a start timing.

FIG. 10 is a timing chart illustrating the operation of the device that generates start timing.

FIG. 11 is a diagram showing a state in which the self-scanning light emitting element array according to the present invention is arranged in a staggered manner on the head.

FIG. 12 is a diagram showing an example of an image when a straight line is drawn without shifting the image data on the memory.

FIG. 13 is a diagram showing an example of an image when a straight line is drawn by shifting image data on a memory.

[Explanation of symbols]

2 photosensitive drum 4 charger 6 Optical writing head 8 developer 10 Transfer device 12 cassettes 14 sheets 16 Fixing device 18 Stacker 20 Erase lamp 22 Cleaner 24 Light emitting element array 26 Rod lens array 29 Self-scanning light emitting element array chip 31 bonding pad 33 light emitting device 51-0 to 51-3 NAND gate 52-0 to 52-3 comparator 53-0 to 53-3 memory 54-0 to 54-3 Comparator output 55-0 to 55-3 Start pulse 60 reset pulse 61 φ1 clock pulse 70 counter 80 count data

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yukisa Kusunoda             4-7 28 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture             Within Nippon Sheet Glass Co., Ltd. F-term (reference) 2C162 AE21 AE28 AE47 AF07 AF13                       AF22 AF69 FA04 FA17

Claims (10)

[Claims] 1. A method of driving an optical writing head in which a plurality of time-division driven light emitting element array chips in which a plurality of light emitting elements are arranged in a row are arranged, and a first light emitting point of each light emitting element array is turned on. A method for driving an optical writing head, characterized in that the timing of the adjustment is adjusted by the amount of positional deviation of each light emitting point projected on the photosensitive drum in the sub-scanning direction. 2. The method for driving an optical writing head according to claim 1, wherein the light emitting element array chips are mounted by being arranged along substantially straight lines in one row or two rows. 3. The driving of the optical writing head according to claim 1, wherein the timing of the image data for driving each light emitting element array chip is shifted according to the timing of turning on the first light emitting point. Method. 4. A plurality of time-divisionally driven light emitting element array chips in which a plurality of light emitting elements are arranged in a row are arranged in a staggered pattern, and each light emission in a direction orthogonal to the arrangement direction of the light emitting element array chips. The interval of the light emitting element rows of the element array chip,
In a method of driving an optical writing head in which each light emitting element array chip is mounted by making an integral multiple of the distance on the photosensitive drum that moves in one line time, the timing at which the first light emitting point of each light emitting element array is turned on is on the photosensitive drum. It is adjusted by the amount of positional deviation of each light emitting point projected in the sub-scanning direction, and the timing of the image data for driving each light emitting element array chip is shifted according to the timing of lighting the first light emitting point. Method for driving optical writing head. 5. In order to shift the timing of the image data, the images are arranged in a memory prepared for the image in a shifted manner, and the image data is sequentially read from the memory in the physical memory arrangement order. The method for driving the optical writing head according to claim 3, 6. When data are collectively shifted on a memory prepared for the image and arranged in the memory, data indicating no image writing is written to an address where the image data was not written by the shift. Claim 5
A method for driving an optical writing head according to [4]. 7. A positional deviation amount is stored in a storage means for each chip or for each block in which a plurality of chips are grouped together, and timing is generated using the positional deviation amount stored in the storage means. 7. The optical writing head driving method according to claim 1, wherein the first light emitting point is turned on by using the generated timing. 8. The timing for turning on the first light emitting point is transferred in synchronization with image data for each chip or for each block in which a plurality of chips are grouped together. 5. A method for driving an optical writing head according to any one of 1. 9. The light according to claim 3, wherein the process of shifting the image data and arranging the image data in the memory is performed by software when the image data is expanded on the memory. How to drive the write head. 10. The method for driving an optical writing head according to claim 1, wherein the light emitting element array chip is a self-scanning type light emitting element array chip.